Diaphus hataii Ohe & Araki, 1973

Schwarzhans, Werner, Ohe, Fumio, Tsuchiya, Yuki & Ujihara, Atsushi, 2022, Lanternfish otoliths (Myctophidae, Teleostei) from the Miocene of Japan, Zitteliana 96, pp. 103-134 : 103

Diaphus hataii Ohe & Araki, 1973

Fig. 9J

Diaphus hataii 1973 Diaphus hataii - Ohe & Araki: pl. 49, figs 3, 4.

Diaphus 1976 Diaphus sp. - Takahashi: pl. 17, fig. 5.

Diaphus hataii 1980 Diaphus hataii Ohe & Araki, 1973 - Ohe and Yamaoka: figs 7(?) 8-13.

Diaphus 1980 Diaphus sp. - Ohe & Yamaoka: fig. 14.

Diaphus regani 2000 Diaphus regani Tåning, 1932 - Brzobohatý & Nolf: pl. 3, figs 15-20.

Diaphus hataii 2013 Diaphus hataii Ohe & Araki, 1973 - Schwarzhans and Aguilera, pl. 10, figs 9-16, 17(?) (see there for further synonymies).

Material.

1744 specimens (figured specimens SMF PO 101.139-143): 4 specimens near Tessicho Hattori , Niimi City, Okayama Prefecture, Bihoku Group, late Burdigalian, diatom tone 3A-3B ; 459 specimens, Miya River at Oda and Numa , Tsuyama City, Okayama Prefecture, Takakura FM, levels MS 04.5, MS 05, MS 05.5, MS 06, MS 07, MS 15, MS 22, MS 27, MS 36, MS 52, MS 70, MS 80, MS 90, b, c, d, f9, f10, f40, g, gh, h, j, early Burdigalian, diatom zone 3A-3B ; 243 specimens, Makino River SW of Mashino , Iga City , Mie Prefecture, Makino FM, levels A 1, A 2, late Burdigalian, lower part of planktonic foraminifera biozone N8 ; 91 specimens, Nagano River at Inabacho, Tsu City, Mie Prefecture, Katada FM, levels I 1, I 2, OA1409, late Burdigalian, lower part of planktonic foraminifera biozone N8 ; 931 specimens, Okuna , Mizunami City, Gifu Prefecture, Oidawara FM, early Langhian, diatom zone 4A ; 2 specimens, Kubusu River at Kashio, Toyama City, Toyama Prefecture, Kurosedani FM, level K 5, late Burdigalian, lower part of planktonic foraminifera biozone N8 ; 14 specimens, Yamada River at Dojima and Osedani, Toyama City, Toyama Prefecture, Higashibessho FM, levels H 14, H 20, H 21, late Burdigalian to early Langhian, diatom zone 3A-4A .

Discussion.

Diaphus hataii is by far the most common myctophid otolith-based species throughout the early and early middle Miocene (late Burdigalian and early Langhian) of Japan, and it represents about 73% of all myctophid otoliths studied here. It is characterized by a short rostrum, which is not or only a fraction longer than the antirostrum; a convex inner face; a ratio OL:OH of 1.20-1.35 (adjusted from Schwarzhans and Aguilera 2013); a ratio OCL:CCL of 1.7-2.0; an oscillating dorsal rim of the ostium; 8-12 fine denticles along the ventral rim (adjusted from Schwarzhans and Aguilera 2013); and a more or less strongly developed predorsal lobe. Schwarzhans and Aguilera (2013) used the latter character as an important means by which to distinguish D. hataii from the contemporaneous D. austriacus (Koken, 1891), but the newly available material shows a certain degree of variability, as most species show such predorsal lobe (Fig. 9J, M, O, Q, R ), while others show a moderately developed predorsal lobe (Fig. 9T, V, W ); there are also specimens with a rather regularly curved dorsal rim (Fig. 9Z , AA, AB). We could not recognize sufficient consistency or additional characters that would warrant splitting of D. hataii into separate species. However, this also means that the distinction between D. hataii and D. austriacus becomes less clear. However, the specimens with a regularly curving dorsal rim are also slightly more elongate than the specimens with a distinct predorsal lobe (OL:OH = 1.25-1.35 vs. 1.20-1.25), while specimens of D. austriacus do not exhibit a predorsal lobe and are more compressed (OL:OH = 1.1-1.2, rarely to 1.25). In addition, D. hataii is thinner than D. austriacus (OH:OT = 3.5-4.0 vs. 3.0-3.5) and shows more denticles along the ventral rim of the otolith (8-12 vs. 6-8). We maintain the view that two separate species existed during the late early Miocene (Burdigalian) and middle Miocene (chiefly Langhian), with D. hataii being widely distributed in the tropics and the northern hemisphere from Europe through Central America and Japan, while D. austriacus appears to have been geographically restricted to Europe and the tropical Atlantic. A further potential vicariant species could be D. curvatus Schwarzhans, 1980 in the early and middle Miocene of the South Pacific (New Zealand and Chile; see Biostratigraphic Evaluation chapter).

Figures

Figure 9. A-I: Diaphus cassidiformis (Frost, 1933), SMF PO 101.138, Yatsuo, Toyama City, Kurosedani Formation, level K 5; J-AC: Diaphus hataii Ohe & Araki, 1973; J-L: SMF PO 101.139, Mizunami City, Oidawara Formation; M-N, Q-V: SMF PO 101.140, Tsuyama City, Takakura Formation, levels MS 06, MS 07, MS 52, MS 90; O-P: SMF PO 101.141, Fuchu machi, Toyama City, Higashibessho Formation, level H 20; W-AA: SMF PO 101.142, Makino River, Iga City, Makino Formation, level A 1; AB-AC: SMF PO 101.143, Inabacho, Tsu City, Katada Formation, level ML 2305; AD-AG: Diaphus biatlanticus (Weiler, 1959); AD-AF: SMF PO 101.144, Mizunami City, Oidawara Formation; AG: SMF PO 101.145, Tsuyama, Takakura Formation, level h; AH-AJ: Diaphus sp. 2, SMF PO 101.146, Mizunami City, Oidawara Formation.